mm/mmzone.c

   1 /*
   2  * linux/mm/mmzone.c
   3  *
   4  * management codes for pgdats and zones.
   5  */
   6
   7
   8 #include <linux/stddef.h>
   9 #include <linux/mmzone.h>
  10 #include <linux/module.h>
  11
  12 struct pglist_data *first_online_pgdat(void)
  13 {
  14         return NODE_DATA(first_online_node);
  15 }
  16
  17 struct pglist_data *next_online_pgdat(struct pglist_data *pgdat)
  18 {
  19         int nid = next_online_node(pgdat->node_id);
  20
  21         if (nid == MAX_NUMNODES)
  22                 return NULL;
  23         return NODE_DATA(nid);
  24 }
  25
  26 /*
  27  * next_zone - helper magic for for_each_zone()
  28  */
  29 struct zone *next_zone(struct zone *zone)
  30 {
  31         pg_data_t *pgdat = zone->zone_pgdat;
  32
  33         if (zone < pgdat->node_zones + MAX_NR_ZONES - 1)
  34                 zone++;
  35         else {
  36                 pgdat = next_online_pgdat(pgdat);
  37                 if (pgdat)
  38                         zone = pgdat->node_zones;
  39                 else
  40                         zone = NULL;
  41         }
  42         return zone;
  43 }
  44
  45 static inline int zref_in_nodemask(struct zoneref *zref, nodemask_t *nodes)
  46 {
  47 #ifdef CONFIG_NUMA
  48         return node_isset(zonelist_node_idx(zref), *nodes);
  49 #else
  50         return 1;
  51 #endif /* CONFIG_NUMA */
  52 }
  53
  54 /* Returns the next zone at or below highest_zoneidx in a zonelist */
  55 struct zoneref *next_zones_zonelist(struct zoneref *z,
  56                                         enum zone_type highest_zoneidx,
  57                                         nodemask_t *nodes,
  58                                         struct zone **zone)
  59 {
  60         /*
  61          * Find the next suitable zone to use for the allocation.
  62          * Only filter based on nodemask if it's set
  63          */
  64         if (likely(nodes == NULL))
  65                 while (zonelist_zone_idx(z) > highest_zoneidx)
  66                         z++;
  67         else
  68                 while (zonelist_zone_idx(z) > highest_zoneidx ||
  69                                 (z->zone && !zref_in_nodemask(z, nodes)))
  70                         z++;
  71
  72         *zone = zonelist_zone(z++);
  73         return z;
  74 }